A deterministic density algorithm for pairwise interaction coverage

Pairwise coverage of factors affecting software has been proposed to screen for potential errors. Techniques to generate test suites for pairwise coverage are evaluated according to many criteria. A small number of tests is a main criterion, as this dictates the time for test execution. Randomness has been exploited to search for small test suites, but variation occurs in the test suite produced. A worst-case guarantee on test suite size is desired; repeatable generation is often necessary. The time to construct the test suite is also important. Finally, testers must be able to include certain tests, and to exclude others. The main approaches to generating test suites for pairwise coverage are examined; these are exemplified by AETG, IPO, TCG, TConfig, simulated annealing, and combinatorial design techniques. A greedy variant of AETG and TCG is developed. It is deterministic, guaranteeing reproducibility. It generates only one candidate test at a time, providing faster test suite development. It is shown to provide a logarithmic worst-case guarantee on the test suite size. It permits users to “seed” the test suite with specified tests. Finally, comparisons with other greedy approaches demonstrate that it often yields the smallest test suite.